html,body,.app{
  width: 100%;
  height: 100%;
}

.dragover {
  -webkit-app-region: drag;
}

.no-drag {
  -webkit-app-region: no-drag;
}

.app {
  background: #ccc;
}

.app .custom-header {
  height: 40px;
  width: 100%;
  background: hotpink;
}

.app .custom-header .right-btn {
  position: fixed;
  height: 40px;
  display: flex;
  right: 0;
  align-items: center;
  justify-content: space-around;
  width: 100px;
}

.app .custom-header .right-btn div:nth-child(1) {
  height: 4px;
  width: 20px;
  border: 1px solid #fff;
  border-radius: 5px;
  cursor: pointer;
}

.app .custom-header .right-btn div:nth-child(2) {
  height: 20px;
  width: 20px;
  border: 1px solid #fff;
  border-radius: 5px;
  cursor: pointer;
}

.app .custom-header .right-btn div:nth-child(3) {
  height: 20px;
  width: 20px;
  overflow: hidden;
  border-radius: 50%;
  text-align: center;
  color: #fff;
  line-height: 17px;
  border: 1px solid #fff;
  cursor: pointer;
  user-select: none;
}

.drag {
  width: 600px;
  height: 400px;
  background: #eee;
}


*{
  margin: 0;
  padding: 0;
}